New: Add postfix fixed ordering option

- With the change to camelCase, it is easier to extend the usageof
  optiosn now, and in this case I've allowed the `orderFixed` (formally
  `aaSortingFixed` parameter to be passed in as an object as well as an
  array. As an object the `pre` and `post` parameters are used to
  specify prefix and / or postfix ordering. Useful for gouping.

.datatables-commit-sync

@@ -1 +1 @@
-a2dd5b40d76ce4522b126827c725fdf5fd3d608a
+953038e785e37682aa9fdb4e24402968615d5b4c

media/js/jquery.dataTables.js

@@ -4098,7 +4098,35 @@
 			aiOrig = [],
 			aoColumns = settings.aoColumns,
 			aDataSort, iCol, sType,
-			nestedSort = settings.aaSortingFixed.concat( settings.aaSorting );
+			fixed = settings.aaSortingFixed,
+			fixedObj = $.isPlainObject( fixed ),
+			nestedSort = [],
+			add = function ( a ) {
+				if ( a.length && ! $.isArray( a[0] ) ) {
+					// 1D array
+					nestedSort.push( a );
+				}
+				else {
+					// 2D array
+					nestedSort.push.apply( nestedSort, a );
+				}
+			};
+	
+		// Build the sort array, with pre-fix and post-fix options if they have been
+		// specified
+		if ( $.isArray( fixed ) ) {
+			add( fixed );
+		}
+	
+		if ( fixedObj && fixed.pre ) {
+			add( fixed.pre );
+		}
+	
+		add( settings.aaSorting );
+	
+		if (fixedObj && fixed.post ) {
+			add( fixed.post );
+		}
 	
 		for ( i=0 ; i<nestedSort.length ; i++ )
 		{
@@ -4139,7 +4167,6 @@
 			aoColumns = oSettings.aoColumns,
 			aDataSort, data, iCol, sType, oSort,
 			formatters = 0,
-			nestedSort = oSettings.aaSortingFixed.concat( oSettings.aaSorting ),
 			sortCol,
 			displayMaster = oSettings.aiDisplayMaster,
 			aSort = _fnSortFlatten( oSettings );